The Norwegian Competition Authority has dealt a blow to financial institutions and their advisers by threatening to block the Nkr18bn (€2.3bn) merger of Norwegian banks Gjensidige and DnB.

Norway's competition regulator said it may ban the merger of Gjensidige and DnB, approved by their shareholders in May. It said the deal could lead to less competition, resulting in "higher prices and less efficient utilisation of society's resources".